Mark Cuban
Greatest Wealth – $2.8 Billion at age 50 (and probably half of that after his divorce)
First Job – Bartender


 
Oprah Winfrey
Greatest Wealth – $2.7 Billion at age 54
First Job – Part time radio news broadcaster



Steve Jobs
Greatest Wealth – $5.4 Billion at age 53
First Job – Gopher at Hewlett Packard


 
Michael Dell
Greatest Wealth – $17.3 Billion at age 43
First Job – Dishwasher for a Chinese restaurant


 
Sergey Brin
Greatest Wealth – $18.7 Billion at age 35
First "Job" – Student


 
Bill Gates
Greatest Wealth – $57 Billion at age 53
First Job – Congressional page


 
Warren Buffet
Greatest Wealth – $62 Billion at age 77
First Job – Newspaper delivery boy


 
Henry Ford
Greatest Wealth – $188 Billion at age 57
First Job – Machinist


 
Andrew Carnegie
Greatest Wealth – $298 Billion at age 68
First Job – Textile laborer


 
John D. Rockefeller
Greatest Wealth – $318 Billion at age 74
First Job – Book keeper

 

Via Google search engine.